On January 1, 1863, President Abraham Lincoln took a break from greeting guests as part of a New Year’s tradition, and slipped into his office to sign a controversial document that ultimately would become a cornerstone in America’s continuing battle for democracy: the Emancipation Proclamation. In the midst of the bloody Civil War, where southern states fought hard to protect their right to enslave the Negro people, this lengthy item declared “that all persons held as slaves” within the rebellious states “are, and henceforward shall be free.”

It had its limitations. It applied only to states that had seceded from the Union, but it exempted border states and any part of the Confederacy that had fallen into northern control. More importantly, it depended upon a Union victory.

The document didn’t actually end slavery in the United States. No piece of paper – even one signed by the President…